First Report of Nigrospora Leaf Blight on Sugarcane Caused by Nigrospora sphaerica in China

Abstract

HomePlant DiseaseVol. 102, No. 4First Report of Nigrospora Leaf Blight on Sugarcane Caused by Nigrospora sphaerica in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Nigrospora Leaf Blight on Sugarcane Caused by Nigrospora sphaerica in ChinaY. P. Cui, B. Wu, A. T. Peng, Z. L. Li, J. F. Lin, and X. B. SongY. P. CuiSearch for more papers by this author, B. WuSearch for more papers by this author, A. T. Peng†Corresponding author: A. T. Peng; E-mail: E-mail Address: [email protected]Search for more papers by this author, Z. L. LiSearch for more papers by this author, J. F. LinSearch for more papers by this author, and X. B. SongSearch for more papers by this authorAffiliationsAuthors and Affiliations Y. P. Cui , Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Guangzhou, China B. Wu , Institution of Fruit Tree Research, Guangdong Academy of Agricultural Sciences and Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilisation, Ministry of Agriculture, Guangzhou, China A. T. Peng † Z. L. Li J. F. Lin X. B. Song , Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Guangzhou, China. Published Online:12 Feb 2018https://doi.org/10.1094/PDIS-07-17-1060-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Sugarcane (Saccharum spp.) is an economically important crop contributing about 80% of world sugar production, which has been widely planted in southern China, including Guangxi, Fujian, and Guangdong provinces (Raza et al. 2010). In December 2016, during our survey in the field in Guangzhou (112°57′ to 114°3′ E, 22°26′ to 23°56′ N), Guangdong, yellow and blighted symptomatic leaves were observed on symptomatic sugarcane plants, and the color of the leaf sheaths had turned red while the normal type should be white. In May 2017, this disease was also observed on sugarcane seedlings grown in the field and in the greenhouse, which were derived from seed pieces collected from symptomatic plants in the field, showing that it was a seedborne disease. To identify the etiology of this disease, symptomatic tissues were surface-sterilized using 70% ethanol for 30 s, 0.2% NaClO for 2 to 3 min, then rinsed three times in sterile water, and plated on potato dextrose agar (PDA). The fungal colonies were initially white and later turned grayish-brown with the onset of sporulation. The mycelia were separated, branched, and black to white in color. The conidia were black, single-celled, and spherical (10.2 to 15.8 μm in diameter), borne on a hyaline vesicle at the tip of each conidiophore. Genomic DNA was extracted from the cultured fungal isolate using genome extraction kit (Axygen, U.S.A.), then amplified using fungal conserved primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (White et al. 1990), and the amplified segments were sequenced and compared with the GenBank database through a BLAST search. The result showed that our sequence shared 100% nucleotide similarity with that from Nigrospora sphaerica (GenBank accession no. KM893076.1). According to Koch’s postulates, pathogenicity tests were conducted on 4- to 5-leaf sugarcane seedlings through both wound inoculation and non-wound inoculation methods. Plants were cultured in a growth chamber (Keli HPX-280H-A, China) at 28°C with 80% humidity. After 20 days, the leaf sheaths wound inoculated with the putative pathogen turned red, the leaves of the plants turned blighted as those observed in the field, and no symptom was observed on any plant wound- or non-wound inoculated with PDA or any plant non-wound inoculated with the putative pathogen. N. sphaerica was repeatedly isolated from symptomatic seedlings wound-inoculated with the putative pathogen but not from any plant inoculated with PDA or non-wound inoculated plants. Thus, N. sphaerica should be responsible for the Nigrospora blight we observed on the sugarcane plants. N. sphaerica has been reported to cause leaf blight on blueberry in Argentina (Wright et al. 2008), sesame in China (Zhao et al. 2014), and tea in India (Dutta et al. 2015). However, to our knowledge, this is the first report of Nigrospora leaf blight caused by N. sphaerica on sugarcane in China.